Cisco ONS15454 and ONS15327 running ONS before 3.4 uses a "public" SNMP community string that cannot be changed, which allows remote attackers to obtain sensitive information.
http://www.securityfocus.com/bid/6081
http://www.iss.net/security_center/static/10507.php
http://www.cisco.com/warp/public/707/ons-multiple-vuln-pub.shtml